• October 20, 2026

  • 4:00 PM (CST): van Hove singularity engineering via homo- and hetero-strain in twisted bilayer graphene

    • Speaker: Dinesh Kumar Yadav (Department of Physics and Astronomy, University of Utah)

    • Abstract

      • Researchers are increasingly exploring moiré materials because of their fascinating properties.

        However, their remarkable flexibility raises questions about how these materials react to

        mechanical strain, particularly because inherent strain during fabrication can lead to variations

        between samples. To address this, we have developed a method to fabricate samples on flexible

        substrates and apply homo-strain by displacing them out of plane. We can apply this strain to

        single-layer graphene Landau levels up to several percent, as a result of which the Fermi velocity

        changes. By carefully calibrating the strain, we can manipulate the Hofstadter butterfly in twisted

        bilayer graphene (TBG) samples away from the magic angle. Wang et al. showed that uniaxial

        hetero-strain arising during sample fabrication splits the otherwise degenerate van Hove

        singularity (vHS) of TBG into three. In our samples, we study the behavior of the three vHS in

        TBG with applied isotropic strain. We find non-intuitive shifts in the energy of the three vHS with

        strain, suggesting that the main effect of our applied homo-strain in these samples is to rotate the

        axis of the hetero-strain. Our work helps elucidate the variability in moiré materials and methods

        to ameliorate it

  • 4:30 PM (CST): Spectrally resolved imaging of exciton and biexciton diffusion in monolayer WSe2

    • Speaker: Sheikh Parvez (Department of Physics, Montana State University)